Radio resource management

ABSTRACT

A method for use in a network covering a region, said region comprising a plurality of areas, a user being assigned to at least oen of said area and having associated therewith a plurality of candidate areas to which the user may be assigned, said method comprising the steps of receiving information identifying said plurality of candidate areas; estimating for each candidate area a parameter, said parameter assuming that said user is assigned to said candidate area; and prioritising said plurality of candidate areas which takes into account the estimated value of said parameter.

FIELD OF THE INVENTION

[0001] The present invention relates to a radio resource manager and amethod of radio resource management.

BACKGROUND OF THE INVENTION

[0002] It has been proposed that in the future wireless communicationsnetworks will consist of more than one radio access technology, such asWCDMA (wideband code division multiple access), GSM/EDGE (global systemfor mobile communication) or the like. By exploiting the different radioaccess technologies, the network as a whole can take advantage of thecoverage and capacity characteristics of each technology. This canresult in a more economic solution and provide the most appropriateradio bearers for a variety of different services.

[0003] In the known radio access networks the management of the radioresources between the systems is performed in a distributed way. Theradio network controllers of the different systems manage the radioresources of each system independently. The efficiency of the resourcemanagement functions is limited by the area under the control of theradio resource controllers of the respective systems.

[0004] It has been appreciated by the inventors that in order to utilisethe existing resources most efficiently, it will be necessary to managethe traffic within the different systems. The prior art arrangement withthe resources being controlled by the radio network controllers of therespective systems is a particular problem with the making of handoverdecision between the systems. This is because the information that canbe taken into account to perform the handover is limited to theresources under the control of each radio resource controller. Within asingle system, the main limitation is the small amount of informationthat is possible to be exchanged between different radio resourcecontrollers. This makes the management of the radio resources in theradio resource controller border areas difficult as the knowledge of thecells under control of the neighboring radio resource controller(s) islimited. In a multi-system environment the information available fromthe cells of another radio access system is even more restricted andthere is no standardised way to check the status of a cell in anothersystem. Moreover, if such an interface would be standardised between forexample two known radio resource controllers, a new radio access systemthat could be introduced later would need separate interfaces to allrelevant radio resource controllers.

[0005] An additional problem is that the separate operation andmaintenance of multiple systems is not cost-efficient and could resultin low resource usage and poor network quality.

[0006] In 3^(rd) generation wireless communications networks a largevariety of different services can be provided to an end user. Contraryto existing 2^(nd) generation networks a continuous coverage or Qualityof Service (QoS) cannot be guaranteed for all services everywhere in thecell because of higher signal-to-interference ratios demanded by highbit rate 3^(rd) generation services. If a cell to which a call isallocated, handed over or the like does not support the required qualityof service, this may mean that the service in question cannot besupported or supported adequately.

SUMMARY OF THE INVENTION

[0007] It is an aim of embodiments of the present invention to addressone or more of the problems discussed above.

[0008] According to one aspect of the invention there is provided amethod for use in a network covering a region, said region comprising aplurality of areas, a user being assigned to at least one of said areaand having associated therewith a plurality of candidate areas to whichthe user may be assigned, said method comprising the steps of receivinginformation identifying said plurality of candidate areas, estimatingfor each candidate area a parameter, said parameter assuming that saiduser is assigned to said candidate area, and prioritising said pluralityof candidate areas which takes into account the estimated value of saidparameter.

[0009] According to a further aspect of the invention there is provideda radio resource manager for use in a network covering a region, saidregion comprising a plurality of areas, a user being assigned to atleast one of said area and having associated therewith a plurality ofcandidate areas to which the user may be assigned, said radio resourcemanager comprising means for receiving information identifying saidplurality of candidate areas, means for estimating for each candidatearea a parameter, said parameter assuming that said user is assigned tosaid candidate area, and means for prioritising said plurality ofcandidate areas which takes into account the estimated value of saidparameter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a better understanding of the invention and as to how thesame may be carried into effect, reference will now be made by way ofexample only to the accompanying drawings in which:

[0011]FIG. 1 shows a network comprising a plurality of different radioaccess technology systems.

[0012]FIG. 2 shows a common radio resource management controlling aplurality of radio access systems.

[0013]FIG. 3 shows the CRRM concept for handover functionality.

[0014]FIG. 4 shows the sequence of events during a handover process.

[0015]FIG. 5 illustrates the prioritisation algorithm of the handoverdecision.

[0016]FIG. 6 illustrates one embodiment of the invention comprising aplurality of CRRMs.

[0017]FIG. 7 illustrates a second embodiment of the invention comprisinga plurality of CRRMs.

[0018]FIG. 8 illustrates a first method for determining throughput.

[0019]FIG. 9 illustrates the mapping of C/I ratios to throughput.

[0020]FIGS. 10a-d illustrate a second method for determining throughput.

[0021]FIG. 11 shows a graph of downlink transmission power against loadin a third method for determining throughput;

[0022]FIG. 12 illustrates a fourth method for determining throughput.

[0023]FIG. 13 shows a modification to the method illustrated in FIG. 12.

[0024]FIG. 14 shows an GSM cell load.

[0025]FIG. 15 shows a graph of bit error rate as a function of carrierto interference ratio.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

[0026] Reference is made to FIG. 1 which shows a network comprising aplurality of different radio access technologies. A mobile station 2 orthe like user equipment is able to use more than one radio accesstechnology. It should be appreciated that the mobile station may in factbe stationary and may for example be a PC, personal digital assistant(PDA) or the like.

[0027] In the example shown, the radio access technologies are macro,micro or pico systems 4, 6 or 8 respectively. These different systemswill have different sizes of cells with macro cells being much largerthan pico cells. Usually the coverage area of one macro cell overlapswith several micro and/or pico cells. Different radio access technologysystems can also be used within the macro, micro and pico systems. Inthe example shown, the different radio access technologies compriseGSM/EDGE 10, WCDMA 12, WLAN 14 (wireless local area network) or TDD 16(time division duplex). It should be appreciated that this is by way ofexample only and any of the systems or radio access technologies can beomitted and/or any other suitable technologies or the like may be usedin embodiments of the present invention.

[0028] The mobile station 2 is arranged to be able to communicate withdifferent ones of these systems. In order to get the best out of thedifferent resources, Common Radio Resource Management (CRRM) is providedto perform these tasks. The CRRM is provided by a server but in thisdocument the entity providing the CRRM function will be referred to as aCRRM. This is described in relation to FIG. 2.

[0029] The CRRM 20 is provided by a server. It should be appreciatedthat whilst the CRRM function is described in this embodiment as beingprovided by a single entity, it is possible in alternative embodimentsof the invention that a number of different entities may provide thissame function. Those different entities may be part of the differentsystems. The lur interface may be used with the distributed approach inorder to exchange the necessary network element load information and/orany other information. The load information can be exchanged between theradio network controllers through the lur interface. This interface isdefined between radio network controllers. However it should beappreciated that the same or similar interface could be defined betweenfor example radio network controller and base station controllerinterfaces and base station controller to base station controllerinterfaces.

[0030] The CRRM 20 is arranged to be connected to each of the differentsystems which, in the embodiment shown in FIG. 2, comprise a WCDMAsystem 12, a GSM/EDGE system 10, a TDD system 16 and IP RAN (internetprotocol radio access network) system 22. The CRRM 20 also receivesinformation from and sends information to the operation and maintenanceentity 24 for the network as a whole.

[0031] The interfaces between CRRM 20 and different systems 10, 12, 16,22 are preferably made from the elements which are handling radioresource management in those systems. These elements are radio networkcontroller (RNC) in WCDMA networks, base station controller (BSC) inGSM/EDGE networks and cell resource servers (CRS) or some other radioresource controller in IP RAN networks. These elements are mentionedonly as examples of the controllers and the term radio resourcecontroller is intended to include all of these elements in thisdocument.

[0032] The CRRM 20 is a policy manager which controls the access to theradio resources. As will be described in more detail hereinafter one ofits tasks is the prioritization of the candidate target cells inhandover and call setups. The main advantages of the CRRM 20 are:

[0033] Load sharing for efficient usage of resources

[0034] Interference distribution to provide higher spectral efficiency

[0035] Improved quality of service (QoS) management. With seamlessintegration of radio technologies based on QoS management the optimumend user performance can be achieved.

[0036] Since the characteristics of different radio access systems aregenerally quite different, a common language for signalling, handoveralgorithms, harmonized load indicators and the like should preferably bedefined between the different systems and the entity(ies) in charge ofcommon radio resource management functionality to avoid defining newinterfaces if a new radio access system were to be used by network.

[0037] The cell prioritisation algorithm which can be used in CRRM tochoose or assign the optimum target cell for connection in call setup,idle mode and in handovers/cell-reselections or the like will now bedescribed.

[0038] In a mobile communication environment, when a mobile station thatis holding up a connection goes out of a certain coverage area or thenetwork has some other reasons for moving the mobile station to anothercell, handover/cell-reselection is required. In the situation where morethan one radio access technology and/or more than one service withdifferent QoS requirements exist, the handover/cell-reselection decision(the decision if and to which cell the connection or connections shouldbe handed over) is not as straightforward as in the case of the priorart mobile environment where just one radio access system exists andwhere the traffic consists mostly in speech services. Similar challengeexists in the call setup where the call is camping on the cell to whichit was connected in idle mode.

[0039] In the latter case, the call setup candidates may be sent to theCRRM 20 which chooses the optimum cell for connection.

[0040] A load threshold may be used to trigger a directed retry, insteadof using a directed retry only when the cell is fully congested. Ifreliable idle mode mobile measurements from available cells are known bythe system before the signalling channel is allocated in the call setup,the call could be directed from the beginning to optimum cell.

[0041] The target cell selection in the CRRM 20 is based on aprioritization algorithm that will order the cells included in thecandidate target cell list sent by the respective radio resourcecontrollers of the different radio access systems to the CRRM 20. Thecandidate target cell list is then rearranged according to each cell'sgrade of suitability to hold on to the connection. Also some additionalinformation, such as whether the handover/cell-reselection implies achange of radio access technology, location or routing area, may betaken into account. The reordered candidate cell list will be sent backto the radio resource controller, that will command the actualhandover/cell-reselection process.

[0042] The method embodying the present invention enables the mobilestation to be always connected to the most suitable cell by integratingthe different radio access systems in such a way that the QoSrequirements of the user connection(s) are fulfilled and the networkperformance is optimised in terms of spectral efficiency and trunkingefficiency. In practice this may mean that 1) a higher number of userscan be accepted (and/or or higher bit rates can be achieved) whilemaintaining the connection quality; 2) the number of dissatisfied userscan be minimised; 3) handover/cell-reselection procedures can be morereliable while also minimising the unnecessaryhandovers/cell-reselections and 4) the usage of hardware resourceswithin different radio access systems can be optimised.

[0043] The process carried out by the CRRM 20 for the handover decisionfunction is shown schematically in FIG. 3. The different inputs to theCRRM and which are used by the algorithms of the CRRM are described in amore details below.

[0044] The CRRM will receive periodically or on demand information aboutthe status of cell resources 30. This information can contain forexample:

[0045] 1. Current traffic load of the cell. This information can be usedto check whether the new connection is anticipated as introducing a highload to the target cell. The load information could be divided into:

[0046] Real Time (RT) load. The RT load could be simply measured as:

[0047] Percentage of hardware (HW) utilisation (e.g. taking into accountthe baseband capacity, transmission capacity, digital signal processor(DSP) capacity, spreading code limitations in WCDMA etc.)

[0048] In WCDMA, this could be the relationship between thetransmission/reception (Tx/Rx) power used by the RT users measured bythe system against the target Tx/Rx power. One or other of the uplink(Rx) and downlink (Tx) ratios or both of these could be sent.

[0049] Non-Real Time (NRT) load. NRT load could be measured by measuringthe average delay of NRT users. The average delay should preferably besent separately for each type of NRT traffic QoS class/prioritycombination. This would mean that the following average delays should bereported:

[0050] Average delay experienced by interactive traffic class packetwith traffic handling priority 1.

[0051] Average delay experienced by interactive traffic class packetwith traffic handling priority 2.

[0052] Average delay experienced by interactive traffic class packetwith traffic handling priority 3.

[0053] Average delay experienced by background traffic class packet.

[0054] The reporting of these values could be the relationship of theaverage delay versus the retransmission time of higher layer (logicallink control LLC) frames. Other options for reporting the delay couldbe:

[0055] Average delay value (over different priority classes)

[0056] Weighted average delay, where the weight could be related toscheduling priority of each priority class

[0057] 2. Total load. Total HW utilisation of the cell, or in WCDMA therelationship between total Tx/Rx power measured by the system versus thetarget Tx/Rx power. Information on the uplink (Rx) or the downlink (Tx)or both of these could be sent to the CRRM.

[0058] 3. Cell interference status. The cell interference statisticscould be used to select the most suitable cell in terms of interference.For real time data services with guaranteed throughput this interferencemeasurement could be used to estimate how much of the resources the newservice is going to occupy in the target cell. In this way the CRRMcould, when prioritising different cells in case of a real-time user,approximate the new real time and total loads of each candidate cellbased on the above mentioned load and interference information.

[0059] The cell interference status could be sent for example in termsof:

[0060] Carrier to interference ratio (C/I) with 95 percentage outage,meaning that 95% of the users in the cell are experiencing higher C/Ithan this value. Naturally any other outage value or statistical measurecould also be used.

[0061] Alternatively, the interference measurement could be, forexample, bit error rate (BER) or bit error probability (BEP) outage (orother statistical measure of these).

[0062] The interference value could also be mapped in the radio resourcecontroller into a throughput value which could be then used forestimating the new real-time and total load of the candidate cells.

[0063] Another option to estimate the interference experienced by theuser in the different candidate cells is to send an interferenceestimate per connection related to each candidate cell when an eventsuch as directed retry (DR), handover, cell-reselection or the like hasbeen triggered. DR means a facility in a cellular radio system allowingthe mobile subscriber to make a second attempt at gaining access if thefirst attempt fails due to congestion.

[0064] Methods for estimating interference or potential throughput aredescribed in more detail hereinafter.

[0065] The CRRM 20 can also receive periodically or on demandinformation 32 about the status of other radio access network (RAN)elements such as information related to loading of the gateways etc. Tomap the percentage cell load value to the actual number ofavailable/reserved timeslots or to a particular transmission power, theCRRM needs to know the configuration information of the different cellsand/or configuration information of different RAN elements. Thisconfiguration information should preferably include the cellcapabilities. For example this would include information as to whetherif a particular cell is supporting GPRS (general packet radio service)and/or EDGE (8-PSK modulation) in GSM. This information could bereceived for example from operation and maintainance entity of thenetwork.

[0066] Apart from the configuration information, parameter values suchas power-budget handover margins between different cells (GSM specific)for circuit switched (CS) and packet switched (PS) (or RT and NRT)connections should be known by the CRRM 20. The handover margin isrelated to the power budgets and it is used for avoiding the ping pongeffect between adjacent areas.

[0067] Other information that can be used by CRRM 20 in prioritisingcandidate cells include:

[0068] The received signal strength or link quality information (e.g.RxLev (received signal level) in GSM, received signal code power (RSCP)or energy per chip to interference ratio (Ec/I) in WCDMA) from theserving cell and the directed retry, direct access, handover orcell-reselection candidates prior to such event. This is an important(but not essential to all embodiments of the invention) input whenselecting the optimum cell as this defines whether the mobile station isin the coverage area of particular cell candidate.

[0069] Quality of Service (QoS) requirements of the connection. QoSrequirements, such as a guaranteed throughput requirement should betaken into account when selecting the optimum cell. Throughput can bemeasured as number of bits (or data bits) transferred in one directionacross a section per unit time (e.g. bps).

[0070] Related to QoS requirements, the type of the traffic class(es)associated with the connection should be taken into account. There canbe several packet data protocol (PDP)-contexts associated with oneconnection. In such cases, the target cell priorisation shouldpreferably take into account all the associated contexts.

[0071] Any parameter relating to cell capability may be used inembodiments of the invention, for example the number of transceiversTRXs, target transmitted to received TX/RX power ratio, EDGE/GPRScapability, neighbour cell lists, or initial handover HOthresholds/margins or the like.

[0072] The CRRM 20 also receives information defining the candidate celllist, mobile station information and connection information 34. As willbe described in more detail hereinafter, the CRRM uses the informationwhich it receives to provide a revised candidate target cell list wherethe candidate cells are given a weighting or priority rating.

[0073] The method embodying the present invention will now be describedwith reference to FIG. 4 which illustrates a handover process.

[0074] Once the CRRM 20 receives the candidate target cell list it willgive a priority value or weight to each cell included in this list. Tocalculate this priority value, the CRRM 20 uses an algorithm consistingof linear or nonlinear combination of its inputs, fuzzy logic, neuralnetworks or any other procedure. An example of the prioritizationalgorithm is shown in FIG. 5. The priority Wn assigned to each cellwhich is a target cell for the handover is obtained, as said, as afunction of numerous inputs:

[0075] Wn=f(Cell_Resources_Status, Other_RAN_Elements_Status,QoS_Requirements, MS_Measurements, MS_Classmark, O&M_Settings,Operator_Preferences)

[0076] In the candidate cell prioritizing, the current serving cell isalso included in the candidate list. In this way the CRRM 20 can alsoprevent the directed retry, handover, cell-reselection or the likerequested by radio resource controller if this is unnecessary ornon-optimum.

[0077] The following steps are carried out. It should be appreciatedthat whilst the method is being performed the CRRM may be receiving theinformation discussed previously. In step 1, a handoff trigger isdetected. This may be any of the conventional triggers in knowncommunications systems. In step 2, the candidate target cell list issent to the CRRM. The list is compiled from information received fromthe different radio access systems 10, 12 and 22. Only one radioresource controller reports the candidate list. The candidate cell listis based on the measurement report measured by the mobile station MS.The neighbour cell list in each radio resource controller includes thecells from the other systems as well. Otherwise they could not bemeasured by a user being connected to a cell that belongs to the givenradio resource controller.

[0078] In step 3, the CRRM 20 orders the candidate target cell list,that is put them in the order of priority. This is done using thealgorithm which will be described with reference to FIG. 5. In step 4,the CRRM 20 sends the ordered target cell list to the radio resourcecontroller of the system having the cell with which the mobile stationis currently associated. The radio resource controller then commands thehandover operation based on the candidate cell list. In particular, theradio resource controller will select the cell with the highestpriority. If that cell is not available for some reason, then the cellwith the next highest priority is selected and so on.

[0079] In step 5, the mobile station receives a handover command fromthe radio network controller and in step 6 the connection is handed overto the new cell. That new cell may be in a different radio access systemor the same system. The old connection will be released.

[0080] Reference is made to FIG. 5 which shows the prioritizationalgorithm. In the embodiment shown the algorithm is shown as having Nparts 50 where N is the number of cells on a candidate cell list. Eachpart 50 receives the following information relating to the candidatecell which it is dealing with: the status of the cell, mobile stationmeasurements from cell N 52, other RAN elements status 54 (such asdiscussed previously), and the status of the resources of cell N 56. Thepurpose of the prioritization algorithm is to provide a priority WN forthe cell. The mobile station measurements as well as the identity of thecandidate cells is provided by the candidate cell list 60. Additionally,the radio resource controller also provides for each part of thealgorithm, via input 58, the mobile station classmark and radio accessbearer parameters such as quality of service requirements and/or thelike.

[0081] Each part of the algorithm 50 also receives operator preferences62, and from the operation and maintenance part 64 of the networkparameters for the algorithm and information relating to the networkconfiguration. Based on the information received, each algorithm partcalculates a priority or weight for each candidate cell. Thatinformation from the algorithm parts 50 is compiled into a list 66 whichis sent to the radio resource controller.

[0082] It should be appreciated that the algorithm parts can perform anysuitable algorithm using the received information. The skilled man wouldbe able to devise such an algorithm.

[0083] It should be appreciated that in this document the term radioresource controller is intended to cover any entity in any access systemwhich provides a control function within its radio access system. Forexample, this may be a base station controller (BSC) in a GSM/EDGEsystem, a radio network controller (RNC) in a CDMA system, cell resourceserver (CRS) in a IP RAN system or the like.

[0084] Emergency handovers such as rapid field drop handovers could beperformed without consulting the CRRM 20 so as not to delay procedures.

[0085] As mentioned previously, the method of the invention could beimplemented in centralised or distributed manner. With the distributedsolution, each radio resource controller would be in charge ofperforming the cell prioritisation for the events that are triggered inthe cells controlled by this particular radio resource controller. Withthe distributed solution, it is necessary to exchange network elementstatus information from each radio resource controller to allneighbouring radio resource controllers. With the centralised CRRMsolution, this signalling needs to be sent only from each radio resourcecontroller to the to the corresponding CRRM(s).

[0086] If several CRRMs exist, the signalling between the CRRMs can bedone in a similar way as in case of the distributed CRRM function.Reference is made to FIG. 6 which shows a network comprising two CRRMs20 each of which controls a number of cells or areas 68. The CRRMs 20are arranged to receive information from their cells or areas. The cellsor areas are associated only with one CRRM. The CRRMs 20 are connectedtogether to receive information from one another about border cells orareas.

[0087] The centralised CRRM could also be handling larger areas so thatthe radio resource controllers would send the load information and/orother information to the centralised CRRM from a particular “area”instead of cells. The CRRM would then only choose the best “area” andthe radio resource controller could choose the best cell/resource withinthis area.

[0088] An alternative is shown in FIG. 7 where the radio resourcecontrollers located in the CRRM border areas 68 send the cell statusinformation to several CRRMs 20. Thus, border cells or areas are able toreport to more than one CRRM and report to all the CRRMs which controladjacent areas or cells. The CRRM to CRRM interface is not required.

[0089] Preferred embodiments of the invention combine the arrangement ofFIGS. 6 and 7 so that the cells or areas can report to more than oneCRRM and the CRRMs can communicate with each other. This has theadvantage that one or other of the options can be used. This may dependon the size of CRRM, the available transport capacity, the base stationcapacity or the like.

[0090] It should be appreciated that the different systems may coveradjacent or at least partially overlapping areas. Accordingly the term“border cell” should be construed accordingly to also include cellswithin a network which are adjacent or overlapping cells or a differentsystem.

[0091] The CRRM 20 is arranged to be able to direct the incoming callsto the most relevant candidate cell according to its QoS requirements(for example Radio Access Bearer RAB parameters). Additionally forhandovers or network controlled cell reselections, the capability of thecandidate cells to support the requested QoS should be known. Amongother parameters (e.g. traffic load, Rx level, operator priorities) thethroughput should preferably be estimated for each cell, otherwise noQoS (required throughput) can be guaranteed before the selection of anew cell. The throughput is important to know especially for realtime(RT) services before the call setup or handover is proceed. Similarly,load increase is important to know in order to check if there is enoughcapacity left in a candidate cell, and also to take into account thecapacity differences between cells.

[0092] A method to estimate the throughput in GSM/EDGE cells based onmeasurement reports and Dynamic Frequency and Channel Allocation (DFCA)will now be described.

[0093] The mobile station reports periodically the measurement reportsfrom a number of neighbouring cells, for example 6 strongest or 32 incase of an extended measurement report, to its originating base station.Of course any suitable other number of cells may also be reported. Theoriginating base station or radio resource controller calculates thethroughputs of each of the candidate cells and provides this informationto the CRRM. Analysis/estimation of the C/I ratio and the availableslots (which is the throughput) is done at each time there is a channelallocation, i.e., handover, call setup or the like, using a DFCA one-waycheck. The throughput is defined based on the mobile station measurementreports and channel allocations in each candidate cells (achieved fromDFCA reports between cells).

[0094] Additionally the background interference matrices (BIM) from eachcandidate cell can be used to get more accurate estimates. This requiresthe BIMs to be transmitted to originating cell.

[0095] The estimated C/I values per timeslot can be mapped to actualthroughput values using mapping tables. The number of availabletimeslots is taken into account when maximum throughput value isdefined.

[0096]FIG. 8 illustrates the procedure of estimating the C/I based on MSmeasurement report and DFCA resource tables from other candidate cells.FIG. 9 illustrates how the C/I is mapped to actual throughput pertimeslot.

[0097] The radio resource controller receives the measurement reportfrom the mobile station including the received levels of eachneighbouring cell (6 strongest neighbours and the signal level fromcurrent cell) Up to 32 strongest neighbours could be considered if anenhanced measurement report is used. The radio resource controller(which includes DFCA algorithms) receives also information about thecurrent channel allocation of neighbouring cells (reserved timeslots perfrequency) from table 200. Based on that information the serving radioresource controller makes a table 202 for each candidate cell of all thephysical channels (timeslots/transmitters) showing all the available andoccupied channels.

[0098] The serving radio resource controller (DFCA) can calculate C/Ifor each timeslot/frequency of each neighbouring cell. This procedure isthe same as the DFCA one way check although no BIMs of neighbouringcells are used.

[0099] To calculate the C/I's only for the largest multislot group isnot the only way to proceed. It should be noted that for example 3 slotswith better average C/I can result higher throughput than 4 slots withworse C/I.

[0100] Accordingly, in addition to the largest multislot group the C/Ivalues can be also calculated for one or more of the next bestcombinations of timeslots. It should be appreciated that this is onlyone method of calculating the C/I ratio and any other suitable methodmay alternatively be used.

[0101] Based on the average C/I and the maximum number of availableslots (it is implementation issue whether the slots need to besequential or not), the radio resource controller calculates athroughput measure for each candidate cell. This is sent to the CRRM. Inaddition, an average C/I per timeslot value can be sent to the CRRM.This can then be mapped to throughput per timeslot in the CRRM inaccordance with FIG. 9.

[0102] Reference is made to FIG. 8 which shows the procedure forestimating the carrier to interference ratio based on the mobile stationmeasurement reports and the DFCA resource tables from the othercandidate cells. Firstly, in step 1, the resource tables 200 for eachcell for each frequency are defined. The tables 200 have an entry foreach frequency f and for each time slot T. Next, a table 202 is definedin step 2 which defines a resource table for each cell for eachtransmitter. In other words, the table includes information on eachtransmitter with respect to the available time slots. The first table200 thus includes an entry for each frequency and time slot as towhether or not a transceiver is using that time slot on that frequencyand, if so, the identity of that transceiver. If a given frequency andtime slot are not being used, the table may be left blank or have anyother suitable indication that the time slot on that frequency isavailable.

[0103] The second table 202 sets out for each transceiver, which timeslot is being used by the respective transceivers.

[0104] In the third step, step 3, the largest set of subsequent timeslots or multislots is selected. In the example shown in table 202, thatwould be timeslots T₁ to timeslot T₄.

[0105] In step 4, the carrier to interference ratio for each frequencyand an associated slot that can accommodate the multislots iscalculated. This is based on the other candidate cells resource tablesand measurements reports. This is shown in the third table 204. As canbe seen, the third table 204 is based on the first table 200 butincludes calculated carrier to interference ratios for time slots T₁ totimeslot T₄ in selected ones of the frequencies. The frequencies whichare selected are those which have all of the timeslots T₁ to T₄ empty.The information from the other cells, which is in a table similar totable 200 are used. The carrier to interference ratio is calculatedusing the following equation:

C/I=own cell (cell n) signal strength RxLev (C) divided by the average(decibels) or the worst (highest) value of measured levels (I) fromother cell levels.

[0106] If any measured cell (n−1) have the same timeslot in use itshould be considered as interference in cell n.

[0107] In step 5, the best average carrier to interference value isselected.

[0108] The average carrier to interference ratio can be mapped to ageneric throughput measure and multiplied by the number of timeslots.This is done in step 6. In this regard, reference is made to FIG. 9which gives an example of how the carrier to interference ratio can bemapped to throughput. In particular, FIG. 9 shows a graph withthroughput per timeslot mapped against carrier to interference ratio.

[0109]FIG. 9 is showing different statistics gathered for differentmulti coding schemes. This graph can be used for estimation of thethroughput when C/I is known. As can be seen from the graph, the greaterthe interference and noise the less the throughput (so another cellcould be better). In more detail, FIG. 9 illustrates the linkadaptation: the better C/I the less channel/error coding can be used andthe better the throughput. The opposite is also true, the lower C/I themore robust the coding scheme that is required. This graph/table shouldbe in CRRM or in radio resource controller.

[0110] This method can be used in any network where DFCA is used.However, in the prior art DFCA report from neighbouring cells, noinformation about transmitters is received. Therefore to use theembodiment of the present invention, some extra information is added tothe DFCA reports from the neighbouring cells, namely the number of usedtransmitters for each frequency/slot and the total number oftransmitters in each cell.

[0111] In this next embodiment a distributed method to estimate thethroughput in GSM/EDGE cells based on measurement reports and DynamicFrequency and Channel Allocation (DFCA) is described. FIGS. 10a-c showthe procedure for estimating the C/I (maximum throughput) in eachcandidate cell based on the distributed mobile station measurementreport and the DFCA resource tables of each candidate cell (and BIMs).As with the previous embodiment, FIG. 9 illustrates how the C/I ismapped to actual throughput per timeslot.

[0112] As shown in FIGS. 10a-c the following steps are carried out.

[0113] The mobile station measures the signal strength of a number ofneighbouring cells, for example six or 32 strongest neighbour cells inthe case of an extended measurement report, and the current cell. Ofcourse in alternative embodiments of the invention, any other suitablenumber of measurements can be used. The mobile station reportsperiodically the measurement reports to its originating base station.

[0114] The originating base station utilises a DFCA one-way check, i.e.,estimates the maximum throughput based on the measurement report and theDFCA background interference matrix (BIM).

[0115] The originating base station sends the measured values obtainedin the previous step to each cell on the candidate list. The candidatecells estimate their maximum throughput based on the measurements andBIM's. This is done by each cell finding its largest set of possibletime slot combination available (sequential multislots or scattered,depending on implementation). Each cell then calculates average C/I forthose slot combinations using both measured values and BIM values (forcells not in the measurement report). The average estimated C/I valuesper timeslot are mapped to actual throughput per timeslot values usingmapping tables. This can be done in the same way as described inrelation to the previous embodiment. The number of available timeslotsis taken into account when maximum throughput value is defined.

[0116] In some embodiments, the maximum throughput is needed only if theimplementation requires subsequent timeslots. Otherwise the throughputper timeslot may be enough.

[0117] Each cell then sends the calculated throughput (per timeslot orC/I per timeslot) values to the CRRM that can use the values in cellprioritisation process

[0118] This method can be used in any network where DFCA is used. Themeasurement report need to be multicast to other candidate cells andcorrespondingly estimated throughput values are forwarded to the CRRM20.

[0119] A method to estimate the throughput and load increase in WCDMAcells is now described.

[0120] In handovers and call set-up all candidate cells can beprioritised by the CRRM as discussed above. For that purpose all cellsreport several indicators to the CRRM, such as traffic load andthroughput. For low bit rate services such as speech services (e.g. 12.2kbps) the measured load percentage values would be enough todifferentiate the candidate cells even if there are capacity differencesbetween them, but for higher bit rates (e.g. >50 kbps) capacitydifferences (Ptx_target downlink transmission power, number oftransceivers etc) between cells have to be taken into account. Forexample, if there is a GSM candidate cell and a WCDMA candidate cellhaving same load percentage, but different maximum capacity it would bemore desirable to handover to WCDMA (assuming that the otherparameters/indicators included in prioritisation process do not impactthis).

[0121] The WCDMA admission control algorithm is used for estimatingrequired transmission power, that is, the load increase due to a newuser in each WCDMA candidate cell. The required maximum power and mobilemeasurement report (ρ_(c)=E_(c)/I_(o)) can be then used to estimateavailable throughput in each cell, i.e. to check if the cell can supportrequested QoS.

[0122] It is assumed here that the downlink direction will limit theload and throughput due to the asymmetric nature of cell traffic.Accordingly only the downlink estimation is considered here. However, itcould be desirable to estimate the uplink load as well, especially ifmost of the connections generate generally equal traffic in bothdirections. A similar technique can be used for uplink estimation.

[0123] Reference is made to FIG. 11 which shows a graph of downlinktransmission power against load. For each cell there is determined athreshold for maximum planned downlink transmission power, Ptx_target inFIG. 11. Ptx_target defines the optimal operating point of the cell load(100% target load), up to which the admission control of the radioresource controller can operate. When the non-controllable part, that isthe realtime part of transmitted/received power which cannot bedynamically adjusted as NRT, of cell load exceeds the target limit, theadmission control will reject at least those establishment requests,which will mean an immediate uplink UL load increase. Ptx_target isdefined by the radio network planning RNP parameter PtxTarget.

[0124] The total transmission power Ptx_total can be expressed as thesum of the power caused by the non-controllable traffic, Ptx_nc, and thepower caused by the controllable traffic of non-real-time users, Ptx_nrt

P _(tx) _(—) _(total) =P _(tx) _(—) _(nc) +P _(tx) _(—) _(nrt)  (1)

[0125] Hence, the load percentages for both total load (including bothRT and NRT data) and RT load can be calculated in radio resourcecontroller as follows: $\begin{matrix}{{{Load}_{{Total}\%} = {100 \cdot \frac{P_{tx\_ total}}{P_{tx\_ target}}}},{{Load}_{{RT}\%} = {100 \cdot \frac{P_{tx\_ nc}}{P_{tx\_ target}}}}} & (2)\end{matrix}$

[0126] For the RT radio access bearer RAB to be established, theincrease of the non-controllable load ΔPtx_nc should be estimated inorder to achieve an estimated load percentage including the requestedRAB radio access bearer. Then the RT load percentage is: $\begin{matrix}{{Load\_ new}_{{RT}\%} = {100 \cdot \frac{P_{tx\_ nc} + {\Delta \quad P_{tx\_ nc}}}{P_{tx\_ target}}}} & (3)\end{matrix}$

[0127] The increase of the non-controllable load ΔPtx_nc can beestimated by determining the maximum downlink DL transmission power ofthe radio link. Consider a single service call with one radio accessbearer RAB of the requested guaranteed bit rate RI_(max) and the targetE_(b)/N₀=ρ for it. If P_(tx,ref) represents the maximum DL transmissionpower of a reference service (e.g., the 12.2 kbit/s speech service couldbe used as a reference service), RI_(ref) its bit rate and ρ_(ref) itstarget E_(b)/N₀ then the maximum power P_(tx,max) for the radio link isdetermined from the P_(tx,ref) by the equation (in linear form)

ΔP _(tx) =P _(tx,max)=MIN(RI _(max,eff) ·P _(tx,ref) ,P _(tx) _(—)_(DPCH) _(—) _(max)),  (4)

[0128] where the ‘maximum effective bit rate correction factor’ isdefined by $\begin{matrix}{{RI}_{\max,{eff}} = \frac{\rho \cdot {RI}_{\max}}{\rho_{ref} \cdot {RI}_{ref}}} & (5)\end{matrix}$

[0129] where P_(tx) _(—) _(DPCH) _(—) _(max) is the absolute maximum forthe DL DPCH (dedicated physical channel) code channel transmission powerdetermined by the parameter PtxDPCHMax.

[0130] As the maximum downlink DL transmission power for the requestedradio access bearer RAB is defined, it can be used to check or estimatethe maximum bit rate Rmax (=throughput) that can be achieved with giventransmission power P_(tx,max). For this purpose ‘the initial DLtransmission power’ formula $\begin{matrix}{P_{tx} = {\frac{\rho \quad R}{W} \cdot {\left( {{\frac{1}{\rho_{c}} \cdot P_{{tx},{CPICH}}} - {\alpha \cdot P_{tx\_ total}}} \right).}}} & (6)\end{matrix}$

[0131] can be modified. The determination of the transmission powerrequires knowledge about several parameter values. They are obtained asfollows.

[0132] ρ=E_(b)/N₀ is energy-per-bit-per-noise-density for requested bitrate

[0133] ρ_(c)=E_(c)/I₀ is the signal-to-interference ratio per chip ofthe perch channel measured by the terminal (MS measurement report).

[0134] W is the chip rate (3.84 Mchips).

[0135] R is the bit rate, specified by the network.

[0136] Ptx_total is measured by the base station.

[0137] Ptx,CPICH is a radio network planning parameter to determine thetransmission power of the Primary CPICH (common pilot channel). α isdifficult to determine since it depends on diverse factors that maychange rapidly. Preliminary, it might be fixed to 0.5.

[0138] Instead of solving initial transmission power for known bit rateR, the maximum achievable bit rate R_(max) with knowledge of maximumtransmission power P_(tx,max) is determined as follows: $\begin{matrix}{R_{\max} = {\frac{P_{{tx},\max} \cdot W}{\rho \cdot \left( {{\frac{1}{\rho_{c}} \cdot P_{{tx},{CPICH}}} - {\alpha \cdot P_{tx\_ total}}} \right)} = {Throughput}}} & (7)\end{matrix}$

[0139] The implementation of this embodiment, as with the previousembodiments, can be distributed or centralised. In the distributedversion the required MS measurement report values are sent to candidatecells, which in turn calculate the throughput and load increase andforward them to CRRM. In a centralised version the MS measurement reportis sent directly to CRRM where throughput and load increase arecalculated. In this case some cell specific radio network planning (RNP)parameters are also needed by the CRRM, including RI_(ref), ρ_(ref)(target E_(b)/N₀), P_(tx,ref), P_(tx) _(—) _(DPCH) _(—) _(max), α, andE_(b)/N₀ table for different data rates, and they should be kept indatabase within the CRRM server and updated from cells if they arechanged.

[0140] In the following, a similar load increase estimation method forGSM cell is described, with reference to FIG. 14.

[0141] In an example of the load in a GSM cell is illustrated. A timeslot can be fully dedicated to RT/NRT traffic or shared betweendifferent traffic classes. For a real time user the total guaranteedbandwidth is considered, summing every guaranteed piece of bandwidthtogether. The NRT load does not have importance for a RT user, since itcan be flexibly controlled by packet scheduler.

[0142] Each GSM cell has certain number of time, slots (TSL_(max)) to beused for user data, depending on the number of transceivers TRXs in celland the reserved slots. The total load consists of RT and NRT data:

TSL _(total) =TSL _(RT) +TSL _(NRT)

[0143] Hence, the load percentages for both total load (including bothRT and NRT data, both dedicated and shared time slots) and RT load canbe calculated in radio resource controller as follows: $\begin{matrix}{{{{Load}_{{Total}\%} = {100 \cdot \frac{{TSL}_{total}}{{TSL}_{\max}}}},{{Load}_{{RT}\%} = 100}}{\cdot \frac{{TSL}_{RT}}{{TSL}_{\max}}}} & (2)\end{matrix}$

[0144] For the RT RAB to be established with bit rate requirementR_(req) the available throughput per timeslot R_(est,tsi) (based onmobile measurements and BTS statistics) should be estimated in order toestimate new load percentage including the requested RAB. Then the RTload percentage could be approximated as: $\begin{matrix}{{Load\_ new}_{{RT}\%} = {{100 \cdot \frac{{{TSL}_{RT} \cdot R_{{est},{tsl}}} + R_{req}}{{TSL}_{\max} \cdot R_{{est},{tsl}}}} = \frac{{TSL}_{RT} + {TSL}_{est}}{{TSL}_{\max}}}} & (3)\end{matrix}$

[0145] For example: current Load_RT=60%, TSLmax=30, throughput perTSL=25 kbps, requested service=64 kbps${Load\_ new}_{{RT}\%} = {{100 \cdot \frac{{{18 \cdot 25}\quad {kbps}} + {64\quad {kbps}}}{{{30 \cdot 25}\quad {kbps}}\quad}} = {68.5\%}}$

[0146] , the service would need at least multislot of 3 TSL's.

[0147] This does not mean that three time slots would be allocated tothe service, but it would give rough estimate about the load increasedue to new user.

[0148] The throughput estimation may be done on a cell basis, i.e.,collecting statistics of the whole cell area, and using some safe 95%guess of available throughput per timeslot. Alternatively, the ‘real’connection-based maximum throughput for a given user in each candidatecell based on mobile measurements and BTS statistics could be estimated.The estimation could be done for example by using existing DFCAalgorithms in each candidate cells. This may require some additionalsignalling between cells.

[0149] In the next embodiment, a method to estimate the throughput inGSM/EDGE cells based on cell interference statistics, mobile stationlocation and the mobile station's measurement report is used. In thisembodiment, interference statistics (e.g. cumulative distributionfunction with 90-95% outage probability) from on-going calls in eachcell as a function of the location of mobile station are collected. Thecell area (or any other type of area) is divided into smaller areas fromwhere the statistics are collected. The values collected for thestatistics can be based on the actual interference level reported by themobile station or can be based on received bit error rate as a functionof received signal level which can be mapped to interference and stored.Each time there is a channel allocation, i.e., during handoff or callsetup, the C/I (carrier to interference) value can be estimated from themobile station measurement report (which provide the value for C) andthe mobile station location and interference statistics (which providethe value of I).

[0150] The estimated C/I value can be then mapped to throughput pertimeslot. The number of available timeslots is taken into account whenmaximum throughput value is defined.

[0151] If the mobile station location cannot be provided, theinterference statistics can be collected as a function of path loss (thereceived level of the signal from the base station gives a measure ofthe cell radius and an indication of the location of the mobile stationwithin the cell). This may not be as accurate as location basedstatistics, but can provide more accurate estimates than single averagestatistics over the whole cell range.

[0152] Similar statistics could be collected for uplink direction aswell.

[0153] Single statistics of interference, C/I or throughput can becollected for the entire cell. This is not very accurate, since theinterference is not the same over the cell area, and it does not takeinto account interference variation. By adding more accuracy, moreprocessing power and signalling is needed.

[0154]FIG. 12 shows the procedure of collecting interference statisticsas function of mobile station location. As can be seen, the cell 100 issubdivided into a plurality of smaller areas 102. For each of theseareas the carrier to interference ratio is calculated by using themobile station measurement report to provide C and the mobile stationlocation and mobile station measurement report statistics to provide I.If the C/I statistics per geographical area is collected then the C/Ivalue for a new connection is only a function of MS location and notcurrent measured value (C)

[0155] For each small areas having coordinates (X and Y) interference(I) (or C/I statistics) statistics are collected and 90-95% value of thestatistics (curves 110 in FIG. 12) is stored in the table (x vs. y)

[0156] Reference is made to FIG. 13 which shows the procedure forcollecting interference statistics as function Rx_level (pathloss). Inthis embodiment, the cell is divided up into a plurality of ring likeregions at respective distances from the base station. In thisembodiment the carrier to interference ratio is calculated. The carrieris calculated as described in relation to the previous figure. Theinterference value is calculated from the function of the pathloss inthe air interface.

[0157] Reference is made again to FIG. 9 which shows how the carrier tointerference ratios are mapped to throughput.

[0158] The collection of statistics should be implemented at each basestation. Base stations could report interference matrices to the CRRM,which then maps mobile MS measurement reports, mobile station MSlocation and available timeslots to maximum throughput. Alternatively,the mobile station MS measurement reports can be forwarded to eachcandidate cell that calculate corresponding throughput values andforwards them to CRRM.

[0159] There has to be some forgetting factor (that is filtering thedata, for example with an IIR filter:new_stat_value=0.98*old_stat_value+0.02*new_sample) for filtering ofcollected data, since different interference/load conditions appearduring different times of day.

[0160] It should be appreciated that one or more of the methods fordetermining throughput can be used in the same network. Differentsystems may use different methods. It is possible that the same systemmay use more than one method of determining throughput.

[0161] It should be appreciated that in alternative embodiments of theinvention, throughput is not determined but rather other parameters suchas load may be determined. Methods similar to those described may beused to determine the parameter in question.

[0162] A method embodying the present invention will now be described.

[0163] The calculation of signal-to-interference ratio (SIR) can beeither cell or connection based. The connection based estimation canrequire quite significant amount of signalling since it is needed toperform for each allocation (handover, call setup). Cell basedestimation, on the other hand, requires only one single (or more In someembodiments of the present invention) statistics for each cell, whichcan be reported to CRRM along with other periodical reporting such asload. Connection based throughput/SIR estimate may be calculated asfollows:

[0164] Centralised throughput calculation based on DFCA:

[0165] Distributed throughput calculation based on DFCA:

[0166] Throughput calculation based on BEP(Bit error probability) and/orC/I statistics and knowledge of the mobile station MS location:

[0167] The statistical method used in the cells may be as follows:

[0168] Collect BEP values from the measurement reports of each on-goingcall in each GSM/GERAN cell

[0169] Map them to C/I values (FIG. 15) and add power control difference(Max Tx power−actual Tx power) to C/I value. Without DL power control,the BEP pairs (MEAN_BEP, CV_BEP) could be directly mapped tothroughput/TSL according to Table 1 (which is included hereinafter).

[0170] Add the values to C/I statistics

[0171] Report 90-95% value of the C/I statistics to CRRM periodically.

[0172] In CRRM C/I statistics of each cells can be mapped tothroughput/TSL using for example Table 1 (directly C/I to the Throughputtable) depending the capability of the cell. For an EDGE capable cell adifferent mapping table must be used for GMSK-only capable cell. If allthe cells had same capabilities (e.g. EDGE) the cell statistics could becollected directly from individual BEP to provide the throughput/TSLvalues.

[0173] If the proportion of high bit rate users is high in the cell itwould seem much more attractive than one cell with a majority of low bitrate users, and vice versa. This could be solved by collecting thestatistics for a set of traffic classes and reporting those differentvalues to the CRRM separately, or weight the statistics in proportion tothe user distribution.

[0174] Also a benchmark service could be used for statistics purpose.For example, only measurements from AMR 12.2 kbit/s users could becollected in statistics.

[0175] It has been assumed that this kind of reporting is not neededfrom WCDMA cells. However in some embodiments of the invention, thistype of reporting may be used with CDMA cells. TABLE 1 throughput inkbps as a function of average BEP (optimum MCS assumed) GMSK 8PSK Rangeof Range of MEAN log10 (actual log10 (actual CV_BEP BEP BEP) BEP) 0 1 23 4 5 6 7 0 >−0.60 >−0.60 0.0 0.0 0.0 0.0 0.0 0.0 3.4 2.4 1 −0.70- −0.60−0.64- −0.60 0.0 0.0 0.0 0.0 0.0 8.8 6.4 5.6 2 −0.80- −0.70 −0.68- −0.640.0 0.0 0.0 0.0 0.0 11.0 8.8 8.5 3 −0.90- −0.80 −0.72- −0.68 0.0 0.0 0.00.0 15.7 13.0 11.6 10.9 4 −1.00- −0.90 −0.76- −0.72 0.0 0.0 0.0 0.0 17.715.0 14.1 13.6 5 −1.10- −1.00 −0.80- −0.76 0.0 0.0 0.0 21.6 19.1 17.116.1 16.1 6 −1.20- −1.10 −0.84- −0.80 0.0 0.0 26.3 22.4 20.9 19.0 17.918.0 7 −1.30- −1.20 −0.88- −0.84 0.0 0.0 27.3 23.3 22.4 21.0 19.7 19.5 8−1.40- −1.30 −0.92- −0.88 0.0 29.5 28.3 24.8 23.4 22.6 21.4 20.9 9−1.50- −1.40 −0.96- −0.92 33.2 29.5 28.9 26.8 24.1 23.9 23.1 22.6 10−1.60- −1.50 −1.00- −0.96 34.1 29.5 29.2 27.9 26.1 24.8 24.8 24.6 11−1.70- −1.60 −1.04- −1.00 34.8 29.5 29.4 28.7 27.8 26.7 26.4 26.4 12−1.80- −1.70 −1.08- −1.04 36.0 29.6 29.5 29.1 28.5 27.9 27.7 27.9 13−1.90- −1.80 −1.12- −1.08 36.4 29.6 29.5 29.4 29.1 28.7 28.5 28.7 14−2.00- −1.90 −1.16- −1.12 36.7 29.6 29.6 29.4 29.4 29.2 29.2 29.1 15−2.10- −2.00 −1.20- −1.16 37.4 29.9 29.6 29.6 29.5 29.4 29.4 29.3 16−2.20- −2.10 −1.36- −1.20 41.8 36.2 32.1 29.7 29.6 29.6 29.6 29.6 17−2.30- −2.20 −1.52- −1.36 44.3 42.8 41.2 39.7 38.1 36.7 36.7 36.7 18−2.40- −2.30 −1.68- −1.52 44.7 44.5 44.0 43.6 43.2 42.9 42.6 42.5 19−2.50- −2.40 −1.84- −1.68 44.8 44.7 44.7 44.5 44.5 44.4 44.3 44.2 20−2.60- −2.50 −2.00- −1.84 44.8 44.8 44.7 44.7 44.7 44.7 44.7 44.7 21−2.70- −2.60 −2.16- −2.00 44.8 44.8 44.8 44.8 44.8 44.8 44.8 44.8 22−2.80- −2.70 −2.32- −2.16 46.0 46.0 45.9 46.3 46.3 45.8 45.7 45.8 23−2.90- −2.80 −2.48- −2.32 48.9 49.2 49.3 49.4 49.5 49.9 49.6 49.5 24−3.00- −2.90 −2.64- −2.48 51.3 51.3 51.7 51.6 52.1 51.8 52.0 52.1 25−3.10- −3.00 −2.80- −2.64 52.8 53.0 53.0 53.2 53.0 52.9 53.1 53.2 26−3.20- −3.10 −2.96- −2.80 53.7 53.8 53.7 53.8 54.5 54.3 54.0 53.9 27−3.30- −3.20 −3.12- −2.96 55.8 56.1 56.2 56.1 56.2 56.2 56.2 56.6 28−3.40- −3.30 −3.28- −3.12 57.2 57.3 57.2 57.5 57.4 57.4 57.7 57.5 29−3.50- −3.40 −3.44- −3.28 58.1 57.9 58.1 58.3 58.3 58.3 58.4 58.3 30−3.60- −3.50 −3.60- −3.44 58.7 58.6 58.6 58.8 58.8 58.8 58.8 58.8 31<−3.60 <−3.60 58.9 58.8 58.8 58.9 58.8 58.9 58.9 59.0

1. A method for use in a network covering a region, said regioncomprising a plurality of areas, a user being assigned to at least oneof said area and having associated therewith a plurality of candidateareas to which the user may be assigned, said method comprising thesteps of: receiving information identifying said plurality of candidateareas; estimating for each candidate area a parameter, said parameterassuming that said user is assigned to said candidate area; andprioritising said plurality of candidate areas which takes into accountthe estimated value of said parameter.
 2. A method as claimed in claim1, wherein said parameter comprises the total load and/or increase inload in said candidate area.
 3. A method as claimed in any precedingclaim, wherein said parameter comprises throughput.
 4. A method asclaimed in any preceding claim, wherein said prioritising and/orestimating step takes into account the current traffic load in acandidate area.
 5. A method as claimed in claim 4, wherein said currenttraffic load comprises a real time load, a non real time load and/or atotal load.
 6. A method as claimed in any preceding claim, wherein saidprioritising and/or estimating step takes into account the interferencestatus of a candidate area.
 7. A method as claimed in any precedingclaim, wherein said prioritising and/or estimating step takes intoaccount the status of one or more entities in said network.
 8. A methodas claimed in any preceding claim, wherein said prioritising and/orestimating step takes into account configuration information relating toa candidate area.
 9. A method as claimed in any preceding claim, whereinsaid prioritising and/or estimating step takes into account handovermargins between different areas.
 10. A method as claimed in anypreceding claim, wherein said prioritising and/or estimating step takesinto account a parameter indicative of signal strength and/or linkquality.
 11. A method as claimed in any preceding claim, wherein saidprioritising and/or estimating step takes into account the quality ofservice requirements of said user.
 12. A method as claimed in anypreceding claim, wherein said prioritising and/or estimating step takesinto account the traffic class or classes associated with said user. 13.A method as claimed in any preceding claim, wherein said prioritisingand/or estimating step takes into account parameters associated withsaid user.
 14. A method as claimed in any preceding claim, wherein saidprioritising and/or estimating step takes into account the measurementsmade by said user relating to one or more of said candidate areas.
 15. Amethod as claimed in claim 14, wherein said measurements comprise thestrength of signals received from at least some of said candidate areas.16. A method as claimed in any preceding claim, wherein saidprioritising and estimating step takes into account information relatingto channel allocation in at least some of said candidate areas.
 17. Amethod as claimed in any preceding claim wherein in said estimatingand/or prioritising step(s) a carrier to interference ratio iscalculated for at least some of time slots associated with at least oneof said candidate areas.
 18. A method as claimed in claim 17, whereinsaid carrier to interference ratio is calculated using dynamic frequencyand channel allocation algorithm.
 19. A method as claimed in claim 17 or18, wherein background interference values are used to determine saidcarrier to interference ratio.
 20. A method as claimed in any of claims17 to 19, wherein said carrier to interference ratios are mapped tocorresponding throughput values.
 21. A method as claimed in any ofclaims 17 to 20, wherein said carrier to interference ratios and ameasure of available time slots is used to provide throughput, saidparameter comprising throughput.
 22. A method as claimed in any ofclaims 17 to 20, wherein said carrier to interference ratio iscalculated by said candidate areas.
 23. A method as claimed in anypreceding claim, wherein in said estimating and/or prioritising step(s),a number of channels or transceivers used for a given frequency and/ortime slot is determined.
 24. A method as claimed in any of the precedingclaims, wherein in said estimating and/or prioritising step(s), thenumber of channels or transceivers in at least one candidate cell isdetermined.
 25. A method as claimed in any preceding claim, wherein saidarea with which said user is associated is divided into a plurality ofsmaller areas and information relating to each of said smaller areas isused in said estimating and/or prioritising step.
 26. A method asclaimed in claim 25, wherein said information is collected as a functionof user position.
 27. A method as claimed in claim 25, wherein saidinformation is collected as a function of pathloss.
 28. A method asclaimed in any preceding claim, wherein said estimating and/orprioritising step(s) are arranged to determine a required maximum powerfor each candidate cell.
 29. A method as claimed in claim 28, whereinsaid maximum power is determined by an admission control algorithm. 30.A method as claimed in claim 28 or 29, wherein measurements provided bythe user is used with said required maximum power to determine availablethroughput for a candidate area.
 31. A method as claimed in anypreceding claim, wherein said candidate areas include the area to whichthe user is currently assigned.
 32. A method as claimed in any precedingclaim, wherein said user comprises a mobile station.
 33. A method asclaimed in any preceding claim wherein said areas comprise cells.
 34. Amethod as claimed in any preceding claim wherein said network comprisesa plurality of systems.
 35. A method as claimed in claim 34, wherein atleast two of said systems use different radio access methods and/orradio interfaces.
 36. A method as claimed in claim 34 or claim 35,wherein at least two of said systems overlap at least partially.
 37. Amethod as claimed in any preceding claim wherein the estimation andassignment steps are done in a centralised entity.
 38. A method asclaimed in any of claims 1 to 36, wherein said estimation and assignmentsteps are done by a plurality of different entities.
 39. A method asclaimed in claim 39 when appended to claim 34, wherein said plurality ofdifferent entities comprise entities in said different systems.
 40. Aradio resource manager for use in a network covering a region, saidregion comprising a plurality of areas, a user being assigned to atleast one of said area and having associated therewith a plurality ofcandidate areas to which the user may be assigned, said radio resourcemanager comprising: means for receiving information identifying saidplurality of candidate areas; means for estimating for each candidatearea a parameter, said parameter assuming that said user is assigned tosaid candidate area; and means for prioritising said plurality ofcandidate areas which takes into account the estimated value of saidparameter.
 41. A manager as claimed in claim 40, wherein said receivingmeans, estimating means and prioritising means are provided in a singleentity.
 42. A manager as claimed in claim 40, wherein a plurality ofsaid entities are provided.
 43. A manager as claimed in claim 42,wherein at least two of said entities are arranged to be connected. 44.A manager as claimed in claim 40, wherein said receiving means,estimating means and prioritising means are provided by a plurality ofdifferent entities.